Preparation and characterization of the Pyrrones as thermal structural materials

Development of technique for preparing foam materials to be used as thermal structural components in spacecraft constructio

Development and optimization of pyrrone polymers, June 1966 - June 1967

Development and optimization of pyrrone polymer

Improving the Functional Control of Aged Ferroelectrics using Insights from Atomistic Modelling

We provide a fundamental insight into the microscopic mechanisms of the ageing processes. Using large scale molecular dynamics simulations of the prototypical ferroelectric material PbTiO3, we demonstrate that the experimentally observed ageing phenomena can be reproduced from intrinsic interactions of defect-dipoles related to dopant-vacancy associates, even in the absence of extrinsic effects. We show that variation of the dopant concentration modifies the material's hysteretic response. We identify a universal method to reduce loss and tune the electromechanical properties of inexpensive ceramics for efficient technologies.Comment: 6 pages, 3 figure

Thromboembolic and neurologic sequelae of discontinuation of an antihyperlipidemic drug during ongoing warfarin therapy

Warfarin and antihyperlipidemics are commonly co-prescribed. Some antihyperlipidemics may inhibit warfarin deactivation via the hepatic cytochrome P450 system. Therefore, antihyperlipidemic discontinuation has been hypothesized to result in underanticoagulation, as warfarin metabolism is no longer inhibited. We quantified the risk of venous thromboembolism (VTE) and ischemic stroke (IS) due to statin and fibrate discontinuation in warfarin users, in which warfarin was initially dose-titrated during ongoing antihyperlipidemic therapy. Using 1999-2011 United States Medicaid claims among 69 million beneficiaries, we conducted a set of bidirectional self-controlled case series studies-one for each antihyperlipidemic. Outcomes were hospital admissions for VTE/IS. The risk segment was a maximum of 90 days immediately following antihyperlipidemic discontinuation, the exposure of interest. Time-varying confounders were included in conditional Poisson models. We identified 629 study eligible-persons with at least one outcome. Adjusted incidence rate ratios (IRRs) for all antihyperlipidemics studied were consistent with the null, and ranged from 0.21 (0.02, 2.82) for rosuvastatin to 2.16 (0.06, 75.0) for gemfibrozil. Despite using an underlying dataset of millions of persons, we had little precision in estimating IRRs for VTE/IS among warfarin-treated persons discontinuing individual antihyperlipidemics. Further research should investigate whether discontinuation of gemfibrozil in warfarin users results in serious underanticoagulation

Doing gender locally: The importance of ‘place’ in understanding marginalised masculinities and young men’s transitions to ‘safe’ and successful futures

Observable anxieties have been developing about the position of boys and young men in contemporary society in recent years. This is expressed as a crisis of masculinity, in which place is often implicitly implicated, but is rarely considered for its role in the shaping of young men’s practices, trajectories and aspirations. Drawing on research conducted with young people who accessed a range of social care support services, this article argues that transition means different things for young men in different locales and that local definitions of masculinity are required to better understand young men’s lives and the opportunities available to them. The authors argue that home life, street life, individual neighbourhoods, regions and nations all shaped the young men’s identities and the practices they (and the staff working with them) drew on in order to create successful futures and ‘safe’ forms of masculinity. It is suggested that this place-based approach has the potential to re-shape the ‘crisis’ discourse surrounding masculinity and the anxieties associated with young men

Regression modeling of longitudinal binary outcomes with outcome-dependent observation times

Conventional longitudinal data analysis methods assume that outcomes are independent of the data-collection schedule. However, the independence assumption may be violated, for example, when adverse events trigger additional physician visits in between prescheduled follow-ups. Observation times may therefore be associated with outcome values, which may introduce bias when estimating the eect of covariates on outcomes using standard longitudinal regression methods. Existing semi-parametric methods that accommodate outcome-dependent observation times are limited to the analysis of continuous outcomes. We develop new methods for the analysis of binary outcomes, while retaining the exibility of semi-parametric models. Our methods are based on counting process approaches, rather than relying on possibly intractable likelihood-based or pseudo-likelihood-based approaches, and provide marginal, population-level inference. In simulations, we evaluate the statistical properties of our proposed methods. Comparisons are made to \u27naive\u27 GEE approaches that either do not account for outcome-dependent observation times or incorporate weights based on the observation-time process. We illustrate the utility of our proposed methods using data from a randomized controlled trial of interventions designed to improve adherence to warfarin therapy. We show that our method performs well in the presence of outcome-dependent observation times, and provide identical inference to \u27naive\u27 approaches when observation times are not associated with outcomes

Random tree growth by vertex splitting

We study a model of growing planar tree graphs where in each time step we separate the tree into two components by splitting a vertex and then connect the two pieces by inserting a new link between the daughter vertices. This model generalises the preferential attachment model and Ford's $\alpha$-model for phylogenetic trees. We develop a mean field theory for the vertex degree distribution, prove that the mean field theory is exact in some special cases and check that it agrees with numerical simulations in general. We calculate various correlation functions and show that the intrinsic Hausdorff dimension can vary from one to infinity, depending on the parameters of the model.Comment: 47 page

Effect of psoriasis severity on hypertension control: a population-based study in the United Kingdom.

IMPORTANCE: Hypertension is prevalent among patients with psoriasis. The effect of psoriasis and its severity on hypertension control is unknown. OBJECTIVE: To determine the association between uncontrolled blood pressure and psoriasis, both overall and according to objectively measured psoriasis severity, among patients with diagnosed hypertension. DESIGN, SETTING, AND PARTICIPANTS: Population-based cross-sectional study nested in a prospective cohort drawn from The Health Improvement Network (THIN), an electronic medical records database broadly representative of the general population in the United Kingdom. The study population included a random sample of patients with psoriasis (n = 1322) between the ages of 25 and 64 years in THIN who were included in the Incident Health Outcomes and Psoriasis Events prospective cohort and their age- and practice-matched controls without psoriasis (n = 11,977). All included patients had a diagnosis of hypertension; their psoriasis diagnosis was confirmed and disease severity was classified by their general practitioners. MAIN OUTCOMES AND MEASURES: Uncontrolled hypertension was defined as a systolic blood pressure of 140 mm Hg or higher or a diastolic blood pressure of 90 mm Hg or higher based on the blood pressure recorded closest in time to the assessment of psoriasis severity. RESULTS: There was a significant positive dose-response relationship between uncontrolled hypertension and psoriasis severity as objectively determined by the affected body surface area in both unadjusted and adjusted analyses that controlled for age, sex, body mass index, smoking and alcohol use status, presence of comorbid conditions, and current use of antihypertensive medications and nonsteroidal anti-inflammatory drugs (adjusted odds ratio [aOR], 0.97; 95% CI, 0.82-1.14 for mild psoriasis; aOR, 1.20; 95% CI, 0.99-1.45 for moderate psoriasis; and aOR, 1.48; 95% CI, 1.08-2.04 for severe psoriasis; P = .01 for trend). The likelihood of uncontrolled hypertension among psoriasis overall was also increased, although not statistically significantly so (aOR, 1.10; 95% CI, 0.98-1.24). CONCLUSIONS AND RELEVANCE: Among patients with hypertension, psoriasis was associated with a greater likelihood of uncontrolled hypertension in a dose-dependent manner, with the greatest likelihood observed among those with moderate to severe psoriasis defined by 3% or more of the body surface area affected. Our data suggest a need for more effective blood pressure management, particularly among patients with more severe psoriasis

Management of expatriate medical assistance in Mozambique

This paper discusses how Mozambique coped with the health system needs in terms of specialized doctors since independence, in a troubled context of war, lack of financial resources and modifying settings of foreign aid. The Ministry of Health (MOH) managed to make up for its severe scarcity of specialist MDs especially through contracting expatriate technical assistance. Different scenarios, partnerships and contract schemes that have evolved since independence are briefly described, as well as self-reliance option possibility and implications. Lessons learned about donor initiatives aimed at contracting specialists from other developing countries are singled out. The issue of obtaining expertise and knowledge in the global market as cheap as possible is stressed, and realistic figures of cost planning are highlighted, as determined by the overall health system necessities and budget limitations

Polynomial growth in age-dependent branching processes with diverging reproductive number

We study the spreading dynamics on graphs with a power law degree distribution p_k ~ k^-gamma with 2<gamma<3, as an example of a branching process with diverging reproductive number. We provide evidence that the divergence of the second moment of the degree distribution carries as a consequence a qualitative change in the growth pattern, deviating from the standard exponential growth. First, the population growth is extensive, meaning that the average number of vertices reached by the spreading process becomes of the order of the graph size in a time scale that vanishes in the large graph size limit. Second, the temporal evolution is governed by a polynomial growth, with a degree determined by the characteristic distance between vertices in the graph. These results open a path to further investigation on the dynamics on networks.Comment: Phys. Rev. Lett. (in press